Power consumption....

In short, does 2.92GHz idle consume less power than 2.92 under 100% load? I'm curious, as speedstep on my machine only works when its IDLE idle, as in when iTunes is playing, CPU-Z shows the multi jumping up and down repetadly...I've just registered for the LHC@home thing, and it just made me curious...Will the electricity bills go up that much? And theoretically, does a CPU at the same clock speed use more power under load?